In general, the liquid crystal display, a device which may be used to display the desired information such as numbers and characters, is formed by disposing a liquid crystal material between control electrodes generally formed on the inner surfaces of insulated substrates. Normally, at least one substrate and its associated electrode are made of a transparent material. When the liquid crystal material between two opposing electrodes is charged with the alternating pulse voltage, a scattering effect occurs so that the liquid crystal material is colored to form a display in the shape of the electrode overlap. This colored area is displayed by the difference in brightness between the scattered portion and the non-scattered portion of the liquid crystal material as illuminated by an external light source. In such a display device, the backplane pulse signal is continuously applied with a regular period to the common electrode of each segment. When a control signal is applied to a control electrode disposed upon the opposite substrate from the common electrode at a phase difference of 180.degree. from the backplane pulse, the liquid crystal material interposed between the control electrode and common electrode is colored. In the case of a measuring instrument such as a digital multimeter or the like, the operation of a measuring range changeover switch is used to control the development of the control signal to a desired numeral or character segment in the liquid crystal display to therefore display the desired number or character.
The measuring symbol driving circuit in a conventional digital multimeter is composed of a circuit having six switches or less. Such a circuit has a small number of control electrodes thereby rendering it difficult to output the proper measuring symbol driving signals in order to display the measuring symbols on the display device. Therefore, it is difficult to develop a measuring circuit which provides the proper number of measuring functions and ranges. Further, the measuring symbol driving circuit in a conventional digital multimeter utilizing a liquid crystal display as the display for measuring symbols, is composed of diodes and logic elements connected to each output terminal of the measuring range changeover switch. As diodes and logic elements must be connected between output terminals of the measuring range changeover switch and a respective control terminal for its associated measuring symbol, the driving circuit must be complex in construction and therefore has a relatively expensive manufacturing cost.